1. Field of the Invention
This invention relates generally to metal hardness testers and specifically to portable metal hardness testers using the Brinell method of hardness testing.
2. Description of the Prior Art
The portable Brinell metal hardness tester disclosed and claimed in U.S. Pat. No. 3,129,582 has, over the past fifty years, become the standard of the world for portable Brinell metal hardness testers. The U.S. Pat. No. 3,129,582 tester has been and is commercially successful and has been copied prolifically since the '582 patent expired. Portable metal hardness testers that are literally bolt-for-bolt copies of the apparatus disclosed and claimed in U.S. Pat. No. 3,129,582 are readily available all over the world. One need only to perform a Google search for “portable Brinell metal hardness tester” to find literally hundreds of sources of supply of machines that are visually indistinguishable from the apparatus disclosed in U.S. Pat. No. 3,129,582.
The same commercial success and third party copying is true respecting the portable Brinell metal hardness tester disclosed and claimed in the U.S. Pat. No. 4,361,034, which is an improvement over the tester disclosed and claimed in U.S. Pat. No. 3,129,582.
While the portable Brinell metal hardness testers disclosed and claimed in U.S. Pat. Nos. 3,129,582 and 4,361,034 have been commercially highly successful, improvements can always be made even in the most successful of products, including the '582 and '034 portable Brinell metal hardness testers.
An occasional annoyance when calibrating the tester or when changing the hydraulic fluid in the portable Brinell metal hardness tester of the type disclosed in U.S. Pat. Nos. 3,129,582 and 4,361,034 is leakage of hydraulic fluid occurring during the calibration or oil change process. The process is messy in that hydraulic fluid, namely oil, inevitably escapes. Moreover, there is always risk of contamination of the hydraulic fluid in the course of the changing of the fluid and/or calibration of the tester.
Another problem arising occasionally is that overzealous technicians, in the course of manually pumping the tester while making a test, inadvertently or perhaps sometimes semi-intentionally pull the pump handle through a greater range of angular travel than for which the tester was designed, thereby either breaking the pump handle or damaging the internal gears of the oil pump within the tester. In either case, the tester is rendered inoperative until it is repaired.
A third problem in using the testers of the '582 and '034 patents is that of technician tampering with the tester once the tester has been calibrated. Neither the '582 tester nor the '034 tester has any means to detect tampering once the tester has been calibrated.
Yet another minor problem with the testers of '582 and '034 patents is that the handle for the pressure release valve is difficult to grasp. Sometimes it may be necessary for the operator to rapidly release the hydraulic pressure within the tester. The handle for the pressure release valve in both the '582 and '034 patent testers is difficult to grasp by an adult, making quick action in opening the pressure release valve difficult.